Corrected entry: The glass on the windows on skyscrapers like the one in the skyscraper/assassin scene is specially made for high altitude building and is usually very thick (4-6 cm thick, as seen by the section the sniper removes), this means that during the subsequent fight scene it would have been impossible to break that window just by bumping into it. (00:47:10)
Lemoncake
4th Mar 2013
Correction: The glass was not broken by both men "bumping" into it. Patrice's rifle went off during the fight and the bullet shattered the glass.